- Too Much Oil Consumption
- Low Oil Pressure
- High Oil Pressure
- Too Much Bearing Wear
- Increased Oil Temperature
Too Much Oil Consumption
Oil Leakage On Outside Of Engine
Check for leakage at the seals at each end of the crankshaft. Look for leakage at the oil pan gasket and all lubrication system connections. Look for oil that may be coming out of the crankcase breather. This can be caused by combustion gas leakage around the pistons. A dirty crankcase breather will cause high pressure in the crankcase. High pressure in the crankcase will cause leakage of the gaskets and seals.
Oil Leakage Into The Combustion Area Of The Cylinders
Oil leakage into the combustion area of the cylinders can be the cause of blue smoke. There are four possible ways for oil leakage to occur in the combustion area of the cylinders:
- Oil leakage between worn valve guides and valve stems.
- Worn piston rings or damaged piston rings
- Plugged oil return holes
- Improperly installed compression ring
- Oil leakage past the seal rings in the impeller end of the turbocharger shaft.
Too much oil consumption can also be the result if oil with the wrong viscosity is used. Oil with a thin viscosity can be caused by increased engine temperature.
Measuring Engine Oil Pressure
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| Illustration 1 | g00293196 |
1U-5470 Engine Pressure Group | |
An oil pressure gauge that has a defect can give an indication of low oil pressure.
The 1U-5470 Engine Pressure Group can be used to check engine oil pressure.
This tool group has a gauge to read oil pressure in the engine. Refer to Special Instruction, SEHS8524 in order to find instructions for the test procedure.
- The correct amount of 10W-30 Oil must be in the engine. The information in the engine oil pressure graph only refers to that 10 W-30 Oil.
- Connect the 1U-5470 Engine Pressure Group to the main oil manifold at location (1) .
- Run the engine to normal operating temperatures.
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| Illustration 2 | g00595594 |
Oil Manifold On Left Side Of Engine (1) Pressure test location. | |
- Keep the oil temperature constant with the engine at rated rpm. Read the pressure gauge.
Note: Make sure that the engine oil temperature does not rise above115 °C (239 °F).
- Find the point of intersection for the lines on the graph.
- If the results do not fall within the "ACCEPTABLE" pressure range that is given in the graph, the problem must be found. Engine failure or a reduction in engine life can result. Engine failure can result if the engine is operated outside of the "ACCEPTABLE" range.
Note: A record of engine oil pressure should be maintained. Oil pressure should be recorded at regular intervals. This record can be used as an indication of possible engine problems or engine damage. If there is a sudden change in oil pressure that is equal to at least 70 kPa (10 psi), the engine should be inspected. This is an indication of a problem even though the pressure is in the "ACCEPTABLE" range on the graph.
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| Illustration 3 | g00293198 |
Engine oil pressure graph | |
Oil Pressure Is Low
Crankcase Oil Level
Check the level of the oil in the crankcase. Add oil if oil is needed. It is possible for the oil level to be too far below the oil pump supply tube. This will cause the oil pump to not have the ability to supply enough lubrication to the engine components.
Oil Pump Condition
The inlet screen of the supply tube for the oil pump can have a restriction. This will cause cavitation and a loss of oil pressure. Air leakage in the supply side of the oil pump will cause cavitation and loss of oil pressure. If the bypass valve of the oil pump is held in the open position, the lubrication system cannot reach maximum pressure. Oil pump gears that have too much wear will cause a reduction in oil pressure.
Oil Filter Bypass Valves
A restriction in the oil filter may cause the bypass valve for the oil filter to be held in the open position. This will cause a reduction in oil pressure. Remove the bypass valve and clean the bypass valve. Remove the bypass valve bore and clean the bypass valve bore. Install a new Caterpillar oil filter. This will prevent debris from restricting the bypass valve.
Excess Bearing Clearance
Worn parts that have too much bearing clearance can cause low oil pressure. A broken oil line or a disconnected oil passage can cause low oil pressure.
Jets For Piston Cooling
When the engine is operated, the jets for piston cooling direct oil toward the bottom of the piston. This lowers the piston and the ring temperatures. If there is a failure of one of the jets, or if one of the jets is bent in the wrong direction, the piston will quickly seize.
Use the 5P-8709 Cooling Jet Alignment Tool in order to inspect the alignment of the jets.
Oil Pressure Is High
Oil pressure will be high if the bypass valve for the oil pump cannot move from the closed position.
Too Much Bearing Wear
When some components of the engine show bearing wear in a short time, the cause can be a restriction in an oil passage. A broken oil passage can also be the cause.
Check for a restriction in an oil supply passage. If there is a restriction, not enough lubrication is allowed to flow through the passage. The oil pressure gauge may continue to show that there is sufficient oil pressure. This is due to the restriction in the oil passage. Parts will wear early because of this problem.
Increased Oil Temperature
Look for a restriction in the oil passages of the oil cooler. If the oil cooler has a restriction, the oil temperature will be higher than normal when the engine is operated. The oil pressure of the engine will not become low because of a restriction in the oil cooler.
Look for a restriction in the oil passages of the oil cooler. If the oil cooler has a restriction, the oil temperature will be higher than normal when the engine is operated. The oil pressure of the engine will not get low just because the oil cooler has a restriction.